rms25thta:
If I read your post correctly, you're asking two separate questions:
1. If I was the current owner of the kit, what would I do?; and
2. Are your sentimental feelings in wanting the kit back "stupid"?
In regard to the first question, if I was the current owner and you provided the background of the kit and the situation with your mother (as suggested by vintagemore2000), I'd have no problem working out a a transaction that would be beneficial to both parties. The fact that I haven't been using the kit and that they are in fact just "sitting in the corner" of my basement should make this a rather simple decision. However, knowing absolutely nothing about the character of the current owner, it's kind of tough to project what his response to your request might be.
In your post I didn't notice whether or not you informed his wife that you'd love to buy the drums back. If you did, hopefully, she'll provide him with a "heads up" in regard to the pending conversation between the two of you. Hope everything works out well!
In regard to your second concern, I don't think that having "sentimental feelings" is ever a stupid thing. Obviously, everyone is different. However, speaking from personal experience, I currently still possess an accordian from the 1920s that my dad used to play as well as my first drum kit -- a 1963 Ludwig Sky Blue Pearl Clubdate -- that my dad bought me when I was 11 years old. Neither of these items probably mean much to anyone else, but they certainly do to me. Neither will leave my home until they take me out of it in a horizontal position.
Good luck and keep us updated!